Additive compositions for correcting overtreatment of conductivity additives in petroleum fuels

ABSTRACT

Disclosed herein are methods for correcting fuel oil compositions having excess conductivity. The oil compositions comprise a Petroleum Based Component, a Conductivity additive and a Conductivity Correcting Additive.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of International Application No. PCT/US06/35589, filed Sep. 12, 2006, which is incorporated herein in its entirety by reference.

FIELD OF THE INVENTION

This invention relates generally to fuel oil compositions, and particularly relates to additives which can be utilized to correct excessive conductivity in hydrocarbon fuels. The invention further relates to a method of using such compositions.

BACKGROUND OF THE INVENTION

A critical issue confronting the hydrocarbon fuel industry is the introduction of Ultra Low Sulfur (ULS) fuels. The processes utilized to diminish sulfur content of fuels can also affect other fuel properties. A fuel property which is directly impacted by such processes is fuel Electrostatics.

Fuel electrostatics is the ability of a hydrocarbon to transport or dissipate charge accumulated in the material. Fuel electrostatics directly affects the probability of an incident (fire or explosion) due to Static Discharge Ignitions (SDI). The real risk associated with SDI is a paramount safety concern for the fuel industry.

The risks associated with SDI are well documented. In the 1980's and 1990's the American Petroleum Institute (API) compiled reports of road tanker explosions in Europe following the introduction of Low Sulfur Diesel (LSD), despite the use of grounding leads. These incidents were specifically attributed to static charge induced ignition of fuel vapor during fuel transfer operations.

Electrostatics: It is widely known that electrostatic charges can be frictionally transferred between two dissimilar, nonconductive materials. When this occurs, the electrostatic charge thus created appears at the surfaces of the contacting materials. The magnitude of the generated charge is dependent upon the nature of and, more particularly, the respective conductivity of each material. The potential for electrostatic ignition and explosion is probably at its greatest during product handling, transfer, and transportation.

Electrostatic charging is known to occur during solvent or fuel pumping operations. In such operations, the flow of low conductivity liquid through conduits with high surface area or through “fine” filters combined with the disintegration of a liquid column and splashing during high speed tank loading can result in static charging. Such static charging can result in electrical discharge (spark) with catastrophic potential in highly flammable environments.

Countermeasures designed to prevent accumulation of electrostatic charges on a container being filled such as container grounding (i.e., “earthing”) and bonding are routinely employed. However, it has been recognized that grounding and bonding alone are insufficient to prevent electrostatic build-up in low conductivity organic liquids.

Organic liquids such as distillate fuels (diesel, gasoline, jet fuel, turbine fuels, home heating fuels, and kerosene) and relatively contaminant free light hydrocarbon oils (organic solvents and cleaning fluids) are inherently poor conductors. Static charge accumulates in these fluids because electric charge moves very slowly through these liquids and can take a considerable time to reach a surface which is grounded. Until the charge is dissipated, a high surface-voltage potential can be achieved which can create an incendiary spark, resulting in an ignition or an explosion.

The risk of static discharge ignition is further compounded by the newly enacted legislation designed to improve emissions characteristics from combustion of fossil fuels.

In order to meet emissions and fuel efficiency goals, automotive original equipment manufacturers (OEM's) are investigating the use of NOx traps, particulate traps and direct injection technologies. Such traps and catalyst systems tend to be intolerant to sulfur. This coupled with the demonstrated adverse environmental consequences of burning sulfur rich fuels has resulted in a global effort to reduce the sulfur content of fuels (Reference World-Wide Fuel Charter, April 2000, Issued by ACEA, Alliance of Automobile Manufacturers, the entire teaching of which is incorporated herein by reference). These low sulfur and ultra-low sulfur fuels are becoming increasingly necessary to ensure compliance with emissions requirements over the full useful life of the latest technological generation of vehicles. Governments are also introducing further legislation for the reduction in particulate matter and fuel emissions.

In the United States, the Environmental Protection Agency (EPA) regulations require the sulfur content of on road fuel to meet Ultra Low Sulfur specification, specifically less than 15 ppm by mass of sulfur in the finished fuel. Similar regulations are also in place globally.

The method most commonly utilized to reduce the sulfur content of fuels is described as hydro treating. Hydro treating is a process by which hydrogen, under pressure, in the presence of a catalyst, reacts with sulfur compounds in the fuel to form hydrogen sulfide gas and a hydrocarbon. However, hydro treating to reduce sulfur content results not only in the removal of sulfur from the fuel but also the removal of other polar compounds which normally increase the conductivity characteristics of the fuel.

Generally, a non-hydro treated fuel has conductivity in the range of 10 to about 30 pS/m², whereas, a hydro treated fuel (below 15 ppm limit) is normally below 1 pS/m². Conductivity below <3 pS/m greatly increases the risk of catastrophic electrostatic ignition. (Kattenwinkel, H. D., Electrical Conductivity, will a minimum level be required for all low S fuels in the future, 2nd CEN/TC 19 Symposium Automotive Fuels, 2003. Walmsley, H. L. An assessment of electrostatic ignition risks and filling rules for loading road tankers with low sulfur diesel, Institute of Petroleum, November 2000; the entire teachings of which are incorporated herein by reference).

In order to correct the detrimental effects of hydro treating, refineries and fuel handlers are routinely utilizing Static Dissipaters/Conductivity Improvers. These additives when used properly minimize the risk of electrostatic ignition in hydrocarbon fuels and solvents. There is a great wealth of knowledge and experience regarding the use of Static Dissipaters/Conductivity Improver additives (ASTM D-4865 Standard Guide for Generation and Dissipation of Static Electricity in Petroleum Fuel Systems, and API Recommended Practice 2003—Protection Against Ignition Arising Out Of Static, Lightening, and Spray Currents; the entire teachings of which are incorporated herein by reference). The diversity of additives which have been patented and utilized in the fuel industry exemplifies the importance of risk associated with ignition due to static discharge.

As a consequence of the refinery processes employed to reduce Diesel sulfur and aromatics content, the majority of Diesel fuels marketed today will require treatment with additives to restore fuel electrical conductivity.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to compositions and methods for correcting fuel oil compositions having excess conductivity. The oil compositions can comprise a Petroleum Based Component, a Conductivity Additive and a Conductivity Correcting Additive.

In another aspect, additional additives can be utilized with the conductivity correcting additive added such as: (a) low temperature operability/cold flow additives, (b) corrosion inhibitors, (c) cetane improvers, (d) detergents, (e) lubricity improvers, (f) dyes and markers, (g) anti-icing additives, (h) demulsifiers/anti haze additives, (i) antioxidants, (j) metal deactivators, (k) biocides, and (l) thermal stabilizers The invention further describes a method of using such compositions formulations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical representation of the effect of lubricity additives on Stadis® 425 conductivity response.

FIG. 2 is a graphical representation of the effect of lubricity additives on T 3514 conductivity response.

In describing the embodiments of the invention, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. The technical equivalence of the additional terms will be readily recognized by a person who is skilled in the art pertaining to this invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to fuel oil compositions, comprising a Petroleum Based Component, a Conductivity Additive, and a Conductivity Correcting Additive to correct excess fuel Conductivity. Disclosed herein are suitable Conductivity Correcting Additive compositions and methods directed toward the utilization of these Conductivity Correcting Additive composition.

Petroleum Based Component: In the present embodiment, a Petroleum Based Component is a hydrocarbon derived from refining petroleum or as a product of Fischer-Tropsch processes (well known to those skilled in the art). The hydrocarbon may also be a solvent. The fuel products are commonly referred to as Petroleum Distillate Fuels.

Petroleum Distillate Fuels encompass a range of distillate fuel types. These distillate fuels are used in a variety of applications, including automotive diesel engines and in non on-road applications under both varying and relatively constant speed and load conditions.

Petroleum Distillate Fuel oils can comprise atmospheric or vacuum distillates. The distillate fuel can contain cracked gas oil or a blend of any proportion of straight run, thermally or catalytically cracked distillates. The distillate fuel in many cases can be subjected to further processing such hydrogen-treatment or other processes to improve fuel properties. The material can be described as a gasoline or middle distillate fuel oil.

Gasoline is a low boiling mixture of aliphatic, olefinic, and aromatic hydrocarbons, and optionally, alcohols or other oxygenated components. Typically, the mixture boils in the range from about room temperature up to about 225° C.

Middle distillates can be utilized as a fuel for locomotion in motor vehicles, air planes, ships and boats as burner fuel in home heating and power generation and as fuel in multi purpose stationary diesel engines.

Engine fuel oils and burner fuel oils generally have flash points greater than 38° C. Middle distillate fuels are higher boiling mixtures of aliphatic, olefinic, and aromatic hydrocarbons and other polar and non-polar compounds having a boiling point up to about 350° C. Middle distillate fuels generally include, but are not limited to, kerosene, jet fuels, and various diesel fuels. Diesel fuels encompass Grades No. 1-Diesel, 2-Diesel, 4-Diesel Grades (light and heavy), Grade 5 (light and heavy), and Grade 6 residual fuels. Middle distillates specifications are described in ASTM D-975, for automotive applications (the entire teaching of which is incorporated herein by reference), and ASTM D-396, for burner applications (the entire teaching of which is incorporated herein by reference).

Middle distillates fuels for aviation are designated by such terms as JP-4, JP-5, JP-7, JP-8, Jet A, Jet A-1. JP-4 and JP-5. The Jet fuels are defined by U.S. military specification MIL-T-5624-N, the entire teaching of which is incorporated herein by reference and JP-8 is defined by U.S. Military Specification MIL-T83133-D the entire teaching of which is incorporated herein by reference. Jet A, Jet A-1 and Jet B are defined by ASTM specification D-1655 and Def. Stan. 91 91 the entire teachings of which are incorporated herein by reference.

These petroleum fuels as described can comprise blends with Bio based fuels. The bio based components as part of the fuel blend are commonly known as Bio Diesel. Bio Diesel as defined by ASTM specification D-6751 (the entire teachings of which are incorporated herein by reference) is a fatty acid mono alkyl esters of vegetable or animal oils. Common oils used in Bio Diesel production are Rapeseed, Soya, Palm Tallow, Sunflower, and used cooking oil or animal fats.

The different fuels described (Engine fuels, Burner fuels and Aviation Fuels) each have further to their specification requirements (ASTM D-975, ASTM D-396 and D-1655 respectively) allowable sulfur content limitations. These limitations are generally on the order of up to 15 ppm of sulfur for On-Road fuels, up to 500 ppm of sulfur for Off-Road applications and up to 3000 ppm of sulfur for Aviation fuels.

Conductivity Additive: Static Dissipaters (SD), Conductivity Improver (CI), or Anti Stats (AS) are defined as any chemical species which are either present or added to fuels to increase the conductivity or the rate of charge dissipation in such fuels.

The diversity of additives which have been patented and utilized in the fuel industry exemplifies the importance of risk associated with ignition due to static discharge.

The types of Static Dissipaters/Conductivity Improver additives which have been patented and can be utilized as part of this invention are described as having components derived from the chemical families that include: aliphatic amines-fluorinated polyolefins (U.S. Pat. No. 3,652,238), chromium salts and amine phosphates (U.S. Pat. No. 3,758,283), alpha-olefin-sulfone copolymer class—polysulphone and quaternary ammonium salt (U.S. Pat. No. 3,811,848), polysulphone and quaternary ammonium salt amine/epichlorhydrin adduct dinonylnaphthylsulphonic acid (U.S. Pat. No. 3,917,466), copolymer of an alkyl vinyl monomer and a cationic vinyl monomer (U.S. Pat. No. 5,672,183), alpha-olefin-maleic anhydride copolymer class (U.S. Pat. Nos. 3,677,725; 4,416,668), methyl vinyl ether-maleic anhydride copolymers and amines (U.S. Pat. No. 3,578,421), alpha-olefin-acrylonitrile (U.S. Pat. Nos. 4,333,741; 4,388,452), alpha-olefin-acrylonitrile copolymers and polymeric polyamines (U.S. Pat. No. 4,259,087), and copolymer of an alkylvinyl monomer and a cationic vinyl monomer and polysulfone (U.S. Pat. No. 6,391,070), an ethoxylated quat (U.S. Pat. No. 5,863,466), hydrocarbyl monoamine or hydrocarbyl-substituted poly(alkylenieamine (U.S. Pat. No. 6,793,695), acrylic-type ester-acrylonitrile copolymers and polymeric polyamines (U.S. Pat. Nos. 4,537,601, 4,491,651), diamine succinamide reacted with an adduct of a ketone and SO₂ (β-sutlone chemistry) (U.S. Pat. No. 4,252,542), the entire teachings of which are incorporated herein by reference.

As a consequence of EPA ULS regulation and hydro treating required to meet sulfur and aromatics content requirements, the majority of ultra-low sulfur Diesel fuels marketed today will require treatment with an electrical conductivity additive to ensure safe operation. This will greatly increase the use of static dissipater additives in the general fuel market.

The use of Conductivity Additives can also become mandated by current ballot actions in ASTM. The ballot proposes to modify ASTM D-975 (on road Diesel specification) to require conductivity additives to meet a minimum conductivity of 50 pS/m at time of use in all ground fuels. The new specification can also impose an upper limit on fuel conductivity.

Currently, aviation fuel specification ASTM D-1655 allows the use of conductivity additives in U.S. civil aviation. Conductivity additives are mandated in U.S. military specifications, E.U. military specification (Def Stan. 91 91) and are also required in civil jet fuels in the rest of the world. These specifications not only require a minimum conductivity in the fuel but also have set a maximum conductivity level at which the fuel is fit for purpose. Conductivities outside this limit will make fuel non-conforming to specifications.

It is commonly known that the increased hazard presented by low conductivity organic liquids can be dealt with by the use of specific additives to increase the conductivity of the respective fluid.

However, there are conditions in which elevated levels of conductivity in the fuel can be detrimental to fuel handling and fuel storage equipment which comes in contact with the fuel.

Excess fuel conductivity has detrimental effects on certain aviation fuel gauges. These gauges are sensitive to fuel conductivity and malfunction with high conductivity fuel. The gauges can record erroneous fuel volume readings which can result in in-flight low fuel warning requiring airplanes to make emergency landings.

Accurate measurement of fuel volume in terminal or refinery holding tanks is a critical economic, environmental and safety issue. Over filing of tanks beyond their capacity results in loss of valuable fuel. The spilled fuel can contaminate the environment and must be cleaned up. While both these results have great financial impact on the tank operator, they are minor as compared to the safety risks associated with fuel spills. The fuel spilled as a result of tank overflow can travel great distances from the spill location. The fuel air mixture associated with spills can be ignited by stray sparks or even hot automobile exhaust pipes. There are documented instances of such fires, a particularly catastrophic example occurred in a U.K. tank farm in 2005 causing billions of dollars in damage.

The gauges utilized to measure volumes in bulk fuel tanks can be affected by the conductivity of the fuel. Many of these volume measuring instruments take into consideration the dielectric constant of the fuel when measuring fuel tank volumes. The effect of an over conductive fuel can impede the function of these devices resulting in erroneous volume readings and possible over filling of fuel tanks.

For the reasons described, it would be very beneficial to be able to correct problems associated with fuels having excessive levels of conductivity.

The present invention describes the use of fuel additives specifically matched to alleviate or correct excess conductivity in fuels. The conductivity control is achieved by the use of Conductivity Correcting Additives. The Conductivity Correcting Additives can have a retarding affect on the conductivity enhancement by fuel conductivity additives.

Generally, it is desirable to have additives which do not negatively impact the performance of other additives in the fuel. The present invention utilizes additive chemistries which on their own perform to meet their intended purpose, but when combined in the desired manner allow for the diminishment of excess conductivity in the fuel without adversely affecting other fuel properties.

The invention utilizes the unexpected interaction between Conductivity Correcting Additives and Conductivity Additives to correct high levels of conductivity in fuels.

Suitable compositions that can serve as a Conductivity Correcting Additive are components derived from chemical families that include: long chain fatty acid, derivatives of such fatty acids include, but not limited to, salts (both mineral and organic), amides and esters; polymeric analogs of organic acids known as dimer/trimer acids, derivatives of such polymeric analogs include, but not limited to, salts (both mineral and organic), amides and esters; and poly and alkyl amines (which are generally known as “filming amines”) and their derivatives such as amides, salts, and oxyalkylates.

Suitable Conductivity Correcting Additives considered within the scope of this invention are described by the general formula:

wherein,

-   -   R₁ can be alkyl-linear, branched, saturated, unsaturated, C₁₋₄₀,         aromatic, cyclic, polycyclic;     -   R₂ can be alkyl-linear, branched, saturated, unsaturated, C₁₋₄₀,         aromatic, cyclic, polycyclic, H, or analogs of R₃—NH₂ or R₃—OH;     -   R₃ can be alkyl-linear, branched, saturated, unsaturated, C₁₋₄₀,         aromatic, cyclic, polycyclic, repeating units based on ethylene,         propylene or butylene oxide, or repeating units based on         ethylene, propylene or butylene aziridine;     -   R₄ can be alkyl-linear, branched, saturated, unsaturated, C₁₋₄₀,         aromatic, cyclic, polycyclic, H, R₃—OH, alcohol, ester, or an         acid;     -   X can be O, NH, NR₁, S, or P;         -   Y can be 1-6; and         -   Z can be organic functional groups (H, alcohols, aldehydes,             ketones, acids, esters, amides, amines, imides, ester             amines, amido amines, imido amines, imidazolines,             carbamates, ureas, imines, and enamines) present on the R₁             hydrocarbon backbone.

Specific examples of products which function as Conductivity Correcting Additive are: a condensate product of an alcohol amine and an organic acid, and alkoxylates of dimerized trimerized fatty acids.

Reactions products of an alcohol amine and an organic acid yields a mixture of alcohol amides and ester amines. A common example is described by the reaction:

Depicted is a C₁₈ fatty acid however, other chain length fatty acids (C₈-C₂₂) are also applicable. The alcohol amine depicted is ethanol amine, although other alcohol amines such as di ethanol amine and tri ethanol amine can be utilized. The carbon spacer instead of ethylene can be propylene or butylene. The ratio of amide to ester can vary depending of process conditions.

Dimerized/Trimerized fatty acids are generally described as a mixture of products derived from reactions of unsaturated fatty acids. Chemistries involved in coupling of these acids are known as 2+2, Ene, and Dials Alder reactions. These complex mixtures can subsequently be reacted with ethylene glycol or ethylene oxide to produce the desired Conductivity Correcting Additive.

Currently, the only method available to diminish the level of fuel conductivity is dilution of a high conductivity fuel with a low conductivity fuel. Often this type of correction is physically impossible due to large volumes associated, and lack of free tank space available for dilution. This type of dilution is also unavailable if the fuel is being transported via a pipeline. A Conductivity Correcting Additive can address both pipeline and tank constraint issues by directly being injection either into the tanks or into a pipeline. The Conductivity Correcting Additive can be handled in the customary fashion as other additives currently used in fuels.

The use of a Conductivity Correcting Additive as disclosed in the present invention is unknown in the fuel/fuel additives industries. Furthermore, the concept of using two additives to diminish excess conductivity is also unappreciated in the fuel and additives industries.

The discovery of this interaction is very important in the fuel industry, specifically as it allows the correction of fuels which may have conductivity beyond acceptable specification requirements or equipment tolerances.

It is further considered as part of this invention, a method of decreasing the conductivity of a hydrocarbon fuel or solvent by metering into the fuel, a suitable Conductivity Correcting Additive. Thus, the invention can be practiced by adding to the fuel a mixture of Conductivity Correcting Additive and conductivity additive, or by adding to the fuel in succession, the conductivity additive and the Conductivity Correcting Additive.

The conductivity and Conductivity Correcting Additive additives can be added in any order, and at any point in the fuel production and handling process. That is, for example, the conductivity additive can be added at a refinery and the Conductivity Correcting Additive subsequently added at a terminal or even at a fueling rack. Another example is the blending of two or more fuels where one fuel contains a conductivity additive and another contains a Conductivity Correcting Additive. A further example is the addition to a fuel a single or multi component formulation comprising a conductivity additive and another single or multi component formulation comprising a Conductivity Correcting Additive.

The control of elevated conductivity in fuels will occur once the additives are present in the fuel, regardless of the method, formulation or order in which they were delivered to the fuel.

The Conductivity Correcting Additive in the formulation is specifically chosen to be present in the fuel oil composition in an amount effective to improve the desired fuel properties.

The Conductivity Correcting Additive can be added separately to the fuel in amounts from 1 to 10,000 mg/l of fuel. It can also be added as part of a conductivity/Conductivity Correcting Additive package, or as part of another multi component package and can eventually be present in the fuel between 1 to 1000 mg/l.

It is additionally considered as part of the present invention the combination of the Conductivity Correcting Additive described herein with other additives typically used in fuel oils, these additives being present in such amounts so as to provide their normal attendant functions. A non exclusive list of these additives are: (a) low temperature operability/cold flow additives such as ethylene-unsaturated ester copolymers, comb polymers containing hydrocarbyl groups pendant from a polymer backbone, polar nitrogen compounds having a cyclic ring system, hydrocarbyl, hydrocarbon polymers such as ethylene alpha-olefin copolymers, polyoxyethylene esters, ethers and ester/ether mixtures such as behenic diesters of polyethylene glycol, (b) corrosion inhibitors, such as fatty amines, poly amines and amides there of known as filming amines, and polymers of fatty acids known as dimmer trimer acids, (c) cetane improvers such as 2-ethyl hexyl nitrite (2EHN) and di tert butyl peroxide (DTBP), (d) detergents, (e) lubricity improvers, such as components derived from chemical families that include: long chain fatty acid, derivatives of such fatty acids to include salts (both mineral and organic), amides and esters; dimers/trimers of fatty acids; and poly and alkyl amines (which are generally known as “filming amines”) and their derivatives such as amides, salts, and oxyalkylates, (f) dyes and markers, (g) anti-icing additives such as ethylene glycol monomethyl ether or diethylene glycol monomethyl ether (h) demulsifiers/anti-haze additives such as those produced from a phenol and an aldehyde under acidic or basic polymerization condition (industrially known as resoles or novelacs) and their alkoxylated (ethylene, propylene or butylene oxide) products, (i) antioxidant compounds such as hindered phenols exemplified by 2,6-di-t-butyl-4-methyl phenol (BHT, butylated hydroxy toluene), 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl phenol, 2-t-butyl-4-octyl phenol, 2-t-butyl-4-dodecyl phenol, 2,6-di-t-butyl-4-heptyl phenol, 2,6-di-t-butyl-4-dodecyl phenol, 2-methyl-6-di-t-butyl-4-heptyl phenol, and 2-methyl-6-di-t-butyl-4-dodecy-1 phenol, ortho coupled phenols to include 2,2′-bis(6-t-butyl-4-heptyl phenol); 2,2′-bis(6-t-butyl-4-octyl phenol), and 2,2′-bis(6-t-butyl-4-dodecyl phenol), where BHT is suitable, as are 2,6- and 2,4-di-t-butylphenol and 2,4,5- and 2,4,6-triisopropylphenol for use in jet fuels, (j) metal deactivators such as (1) Benzotriazoles and derivatives thereof, for example, 4- or 5-alkylbenzotriazoles (e.g. tolutriazole) and derivatives thereof; 4,5,6,7-tetrahydrobenzotriazole and 5,5′-methylenebisbenzotriazole, Mannich bases of benzotriazole or tolutriazole, e.g. 1-[bis(2-ethylhexyl)aminomethyl]tolutriazole, 1-[bis(2-ethylhexyl)amin-omethyl]benzotriazole, and alkoxyalkylbenzotriazoles such as 1-(nonyloxymethyl)-benzotriazole, 1-(1-butoxyethyl)benzotriazole and 1-(1-cyclohexyloxybutyl)-tolutriazole, (2) 1,2,4-triazoles and derivatives thereof, for example, 3-alkyl(or aryl)-1,2,4-triazoles, and Mannich bases of 1,2,4-triazoles, such as 1-[bis(2-ethylhexyl)aminomethyl-1,2,4-triazole; alkoxyalkyl-1,2,4-triazoles such as 1-(1-butoxytheyl)-1,2,4-trizole, and acylated 3-amino-1,2,4-triazoles, (3) Imidazole derivatives, for example 4,4′-methylenebis(2-undecyl-5-methylimidazole) and bis[(N-methyl)imidazol-2-yl]carbinol octyl ether (4) Sulfur-containing heterocyclic compounds, for example 2-mercaptobenzothiazole, 2,5-dimercapto-1,3,4-thiadiazole and derivatives thereof, and 3,5-bis[di(2-ethyl-hexyl)aminomethyl]-1,3,4-thiadiazolin-2-o-ne, and (5) Amino compounds and imino compounds, such as N,N′-disalicylidene propylene diamine (DMD), salicylaminoguanadine and salts thereof, (k) biocides, (1) thermal stabilizers.

Low temperature operability/cold flow additives are used in fuels to enable users and operators to handle the fuel at temperatures below which the fuel would normally cause operational problems. Distillate fuels such as diesel fuels tend to exhibit reduced flow at low temperatures due in part to formation of waxy solids in the fuel. The reduced flow of the distillate fuel affects transport and use of the distillate fuels in refinery operations and internal combustion engine. This is a particular problem during the winter months and especially in northern regions where the distillates are frequently exposed to temperatures at which solid formation begins to occur in the fuel, generally known as the cloud point (ASTM D 2500) or wax appearance point (ASTM D 3117). The formation of waxy solids in the fuel will in time essentially prevent the ability of the fuel to flow, thus plugging transport lines such as refinery piping and engine fuel supply lines. Under low temperature conditions during consumption of the distillate fuel, as in a diesel engine, wax precipitation and gelation can cause the engine fuel filters to plug resulting in engine inoperability. Example of Low temperature operability/cold flow marketed by Innospec Inc. of Newark, Del. is PPD 8500.

Corrosion Inhibitors are a group of additives which are utilized to prevent or retard the detrimental interaction of fuel and materials present in the fuel with engine components. The additives used to impart corrosion inhibition to fuels generally also function as lubricity improvers. Examples of Corrosion Inhibitors marketed by Innospec Inc. of Newark, Del. are DCI 6A, and DCI 4A.

Cetane Improvers are used to improve the combustion properties of middle distillates. As discussed in U.S. Pat. No. 5,482,518 (the entire teaching of which is incorporated herein by reference) fuel ignition in diesel engines is achieved through the heat generated by air compression, as a piston in the cylinder moves to reduce the cylinder volume during the compression stroke. In the engine, the air is first compressed, then the fuel is injected into the cylinder; as the fuel contacts the heated air, it vaporizes and finally begins to burn as the self-ignition temperature is reached. Additional fuel is injected during the compression stroke and the fuel burns almost instantaneously, once the initial flame has been established. Thus, a period of time elapses between the beginning of fuel injection and the appearance of a flame in the cylinder. This period is commonly called “ignition delay” and must be relatively short in order to avoid “diesel knock”. A major contributing factor to diesel fuel performance and the avoidance of “diesel knock” is the cetane number of the diesel fuel. Diesel fuels of higher cetane number exhibit a shorter ignition delay than do diesel fuels of a lower cetane number. Therefore, higher cetane number diesel fuels are desirable to avoid diesel knock. Most diesel fuels possess cetane numbers in the range of about 40 to 55. A correlation between ignition delay and cetane number has been reported in “How Do Diesel Fuel Ignition Improvers Work” Clothier, et al., Chem. Soc. Rev, 1993, pg. 101-108. Cetane improvers have been used for many years to improve the ignition quality of diesel fuels. Example of a Cetane Improvers marketed by Innospec Inc. of Newark Del. is CI-0801.

Detergents are additives which can be added to hydrocarbon fuels to prevent or reduce deposit formation, or to remove or modify formed deposits. It is commonly known that certain fuels have a propensity to form deposits which may cause fuel injectors to clog and affect fuel injector spray patterns. The alteration of fuel spray patterns may cause non uniform distribution and/or incomplete atomization of fuel resulting in poor fuel combustion. The accumulation of deposits is characterized by overall poor drivability including hard starting, stalls, rough engine idle and stumbles during acceleration. Furthermore if deposit build up is allowed to proceed unchecked, irreparable harm may result which may require replacement or non-routine maintenance. In extreme cases, irregular combustion could cause hot spots on the pistons which can resulted in total engine failure requiring a complete engine overhaul or replacement. Examples of Detergents marketed by Innospec Inc. of Newark, Del. are DDA 350, and OMA 580.

Lubricity improver's increase the lubricity of the fuel, which impacts the ability of the fuel to prevent wear on contacting metal surfaces in the engine. A potential detrimental result of poor lubricating ability of the fuel can be premature failure of engine components (for example, fuel injection pumps). Examples of Lubricity Improvers marketed by Innospec Inc. of Newark, Del. are OLI 9070.x, and OLI9101.x.

Fuel lubricity is the ability of the fuel to prevent wear on contacting metal surfaces. Certain diesel engine designs rely on fuel as a lubricant for their internal moving components. The problem of poor lubricity in these fuels is likely to be exacerbated by future engine system developments aimed at further decreasing emissions. This will result in an increase in the fuel oil lubricity requirement relative to requirements for present engines. For example, the use of high pressure unit injectors will likely increase the need for better fuel oil lubricity. Fuel lubricity requirements can be achieved by the use of lubricity additives.

Dyes and Markers are materials used by the EPA (Environmental Protection Agency) and the IRS (Internal Revenue Service) to monitor and track fuels. Since 1994 the principle use for dyes in fuel is attributed to the federally mandated dying or marking of untaxed “off-road” middle distillate fuels as defined in the Code of Federal Regulations, Title 26, Part 48.4082-1(26 CFR 48.4082-1). Dyes are also used in Aviation Gasoline; Red, Blue and Yellow dyes denote octane grade in Avgas. Markers are used to identify, trace or mark petroleum products without imparting visible color to the treated product. One of the main applications for markers in fuels is in Home Heating Oil. Examples of Dyes and Markers marketed by Innospec Inc. of Newark, Del. are Oil Red B4 and Oil Color IAR.

Anti-Icing Additives are mainly used in the aviation industry and in cold climates. They work by combining with any free water and lowering the freeze point of the mixture that no ice crystals are formed. Examples of Anti-Icing additives marketed by Innospec Inc. of Newark, Del. are Dri-Tech and DEGME.

Demulsifiers/Anti Haze additives are mainly added to the fuel to combat cloudiness problems which maybe caused by the distribution of water in a wet fuel by dispersant used in stability packages. Examples of Demulsifiers/Anti Haze additives marketed by Innospec Inc. of Newark, Del. are DDH 10 and DDH 20.

Antioxidants are used to inhibit the degradation of fuels by interaction of the fuel with atmospheric oxygen. This process is known as “Oxidative Instability”. The oxidation of the fuel results in the formation of alcohols, aldehydes, ketones, carboxylic acids and further reaction products of these functional groups, some of which may yield polymers. Antioxidants function mainly by interrupting free radical chain reactions thus inhibiting peroxide formation and fuel degradation. Examples of Antioxidants additives marketed by Innospec Inc. of Newark, Del. are AO 37 and AO 29.

Metal Deactivators are chelating agents that form stable complexes with specific metals. Certain metals (Copper, Zinc) are very detrimental to fuel stability as they catalyze oxidation processes resulting in fuel degradation (increase in gums, polymers, color, and acidity). Examples of Metal Deactivator marketed by Innospec Inc. of Newark, Del. is DMD.

Biocides are used to control microorganisms such as bacteria and fungi (yeasts, molds) which can contaminate fuels. Biological problems are generally a function of fuel system cleanliness, specifically water removal from tanks and low point in the system. Example of Biocide marketed by Innospec Inc. of Newark, Del. is 6500.

Thermal Stabilizers are additives which help prevent the degradation of fuel upon exposure to elevated temperatures. Fuel during its use cycle is exposed to varying thermal stresses. These stresses are: 1) In storage—where temperatures are low to moderate, 0 to 49° C. (32 to 120° F.), for long periods of time, 2) In vehicle fuel systems—where temperatures are higher depending on ambient temperature and engine system, 60 to 70° C. (140 to 175° F.), but the fuel is subjected to these higher temperatures for shorter periods of time than in normal storage, and 3) In (or near) the engine—where temperatures reach temperatures as high as 150° C. (302° F.) before injection or recycling, but for even shorter periods of time. Thermal stability additives protect the fuel uniformity/stability against these types of exposures. Examples of Thermal Stabilizers marketed by Innospec Inc. of Newark, Del. are FOA 3 and FOA 6.

The invention fully discloses the use of Conductivity Correcting Additive additives to control over conductivity of fuels, by selecting and properly matching a Conductivity Correcting Additive to a conductivity additive thereby utilizing their interaction to minimize fuel conductivity in order to meet fuel or operational specifications.

The invention is further described by the following illustrative but non-limiting example.

EXAMPLE

Conductivity Test Method: Conductivity of the fuel is measured by using procedures outlined in ASTM D-2624 Standard Test Methods for Electrical Conductivity of Aviation and Distillate Fuels. The complete method is incorporated herein by reference.

Conductivity Correcting Additive Test Method:

General Additive Survey: The effect on conductivity upon combining other fuel additives with conductivity additives was evaluated. A series of additives available in the fuel industry were added to #2 ULS Diesel containing 1 mg/l of market available conductivity additives. The additives which exhibited the greatest conductivity control response were then reevaluated at higher doses of conductivity additive.

Conductivity Correcting Additive Screen: The base line conductivity of the fuel containing 10 mg/l of conductivity additive was measured. The additives selected from the General Additive Survey were then dosed into a high conductivity fuel (10 mg/l of conductivity additive) at amounts equivalent to 200 mg/l, and 400 mg/l. The conductivity of the fuel containing conductivity additive and Conductivity Correcting Additive was then evaluated.

Static Dissipater I (Stadis® 425): The effect on conductivity upon combining a Conductivity Correcting Additive with Stadis® 425 was evaluated. The conductivity of the fuel with 10 mg/l of Stadis® 425 along with 200 and 400 mg/l of Conductivity Correcting Additive is depicted in FIG. 1.

Analyses of the conductivity control experiments indicate that Conductivity Correcting Additive T 9125, T 9127, T 9137, and R 690 exhibited the best conductivity control properties with Stadis® 425 conductivity additive.

The data clearly exemplifies the need to correctly match Conductivity Correcting Additive and conductivity additive in order to obtain the greatest level of control over high conductivity.

Static Dissipater II (Tolad 3514): The affect on conductivity upon combining a Conductivity Correcting Additive with Tolad 3514 was evaluated. The conductivity of the fuel with 10 mg/l of Tolad 3514 along with 200 and 400 mg/l of Conductivity Correcting Additive is depicted in FIG. 2.

Analyses of the conductivity control experiments indicate that Conductivity Correcting Additive T 9125, and R 690 exhibited the best conductivity control properties with Tolad 3415 conductivity additive.

The data indicates that it is critical to properly select and combine additives to adequately address fuel excess conductivity.

All of the compositions and methods disclosed and claimed herein can be manufactured and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of specific embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the methods described herein without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain compositions which are chemically related can be substituted for the compositions described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims. 

1) A fuel oil composition comprising: a. a Petroleum Based Component, b. a Conductivity Additive, and c. a Conductivity Correcting Additive. 2) The fuel oil composition of claim 1, wherein said Petroleum Based Component is a middle distillate fuel, a jet fuel, or a Fischer-Tropsch fuel. 3) The fuel oil composition of claim 1, wherein said Petroleum Based Component comprises less then about 500 ppm by mass of sulfur. 4) The fuel oil composition of claim 1, wherein said Petroleum Based Component comprises less then about 15 ppm by mass of sulfur. 5) The fuel oil composition of claim 1, wherein said Conductivity Correcting Additive comprises additives selected from the group consisting of: organic acids, polymeric analogs of organic acids and their ester or amides derivatives. 6) The fuel oil component of claim 5, wherein said Conductivity Correcting Additive is represented by general formula:

wherein; R₁ can be alkyl-linear, branched, saturated, unsaturated, C₁₋₄₀; aromatic, cyclic, polycyclic; R₂ can be alkyl-linear, branched, saturated, unsaturated, C₁₋₄₀; aromatic, cyclic, polycyclic, H, or analogs of R₃—NH₂ or R₃—OH; R₃ can be alkyl-linear, branched, saturated, unsaturated, C₁₋₄₀; aromatic, cyclic, polycyclic, repeating units based on ethylene, propylene or butylene oxide, or repeating units based on ethylene, propylene or butylene aziridine; R₄ can be alkyl-linear, branched, saturated, unsaturated, C₁₋₄₀; aromatic, cyclic, polycyclic; H, R₃—OH; Alcohol; Ester; or an Acid; X can be O, NH, NR₁, S, or P; Y can be 1-6; and Z can be organic functional groups (H, alcohols, aldehydes, ketones, acids, esters, amides, amines, imides, ester amines, amido amines, imido amines, imidazolines, carbamates, ureas, imines, and enamines) present on the R₁ hydrocarbon backbone. 7) The fuel oil composition of claim 1, wherein said Conductivity Correcting Additive is present in the fuel between about 10 to about 10,000 mg/l of fuel. 8) The fuel oil composition of claim 1, wherein said Conductivity Correcting Additive is present in the fuel between about 50 to about 1000 mg/l of fuel. 9) The fuel oil composition of claim 1, wherein said Conductivity Correcting Additive is present in the fuel between about 50 to about 300 mg/l of fuel. 10) The fuel oil composition of claim 1, wherein said Conductivity Additive comprises additives selected from the group consisting of: alpha-olefin-sulfone copolymer such as polysulphone and quaternary ammonium salt, polysulphone and quaternary ammonium salt amine/epichlorhydrin adduct dinonylnaphthylsulphonic acid, copolymer of an alkyl vinyl monomer and a cationic vinyl monomer, alpha-olefin-maleic anhydride copolymer class, methyl vinyl ether-maleic anhydride copolymers and amines, alpha-olefin-acrylonitrile, alpha-olefin-acrylonitrile copolymers and polymeric polyamines, and copolymer of an alkylvinyl monomer and a cationic vinyl monomer and polysulfone, a ethoxylated quat, hydrocarbyl monoamine or hydrocarbyl-substituted polyalkylenieamine, acrylic-type ester-acrylonitrile copolymers and polymeric polyamines, and diamine succinamide reacted with an adduct of a ketone and SO₂. 11) The fuel oil composition of claim 1, wherein said Conductivity Additive is present in the fuel between about 0.01 to about 100 mg/l of fuel. 12) The fuel oil composition of claim 1, wherein said Conductivity Additive is present in the fuel between about 0.1 to about 15 mg/l of fuel. 13) The fuel oil composition of claim 1, wherein said Conductivity Additive is present in the fuel between about 0.3 to about 5 mg/l of fuel. 14) A method of controlling the conductivity of a hydrocarbon fuel or solvent by metering into the fuel said Conductivity Correcting Additive of claim
 5. 15) The method of claim 14, wherein said Conductivity Correcting Additive and a Conductivity Additive are metered together. 16) The method of claim 14, wherein said Conductivity Correcting Additive and a Conductivity Additive are metered separately. 17) The fuel composition of claim 1 further comprising additives selected from the group consisting of (a) low temperature operability/cold flow additives, (b) corrosion inhibitors, (c) cetane improvers, (d) detergents, (e) lubricity improvers, (f) dyes and markers, (g) anti-icing additives, (h) demulsifiers/anti haze additives, (i) antioxidants, (j) metal deactivators, (k) biocides, and (l) thermal stabilizers. 18) A method of operating an internal combustion engine such as a compression-ignition engine using as fuel for the engine a fuel oil composition as recited in claim
 1. 19) The method of claim 18, wherein said fuel oil is a middle distillate fuel containing less than 500 ppm by mass of sulfur. 